Refining chitinozoan biostratigraphy through the early and late Aeronian biogeochemical events on Anticosti Island, Quebec, eastern Canada
Bibliographic record
Abstract
Abstract. The Silurian is marked by a series of biogeochemical events that are expressed in the rock record as positive δ13C excursions and that drove turnovers in marine biodiversity. Exploring these events provides a unique window into the functioning of the ancient Earth system. The anomalies in the carbon isotope record provide an excellent stratigraphic tool for global correlations in the Paleozoic. Anticosti Island has an exceptionally well-preserved stratigraphic record of the Ordovician–Silurian boundary interval, allowing for the study of the early and late Aeronian events and their impact on chitinozoan communities. This study fills a historic gap in the chitinozoan biostratigraphic record of Anticosti Island and provides a refined biostratigraphic framework for global Llandovery correlations. A total of 42 samples from the Merrimack, Gun River, Menier, and Jupiter formations near the mouth of the Jupiter River and from two cores (La Loutre and Martin La Mer) in the south-central part of the island are examined. We redefine the Ancyrochitina ramosaspina Local Biozone and document a total of 27 chitinozoan species. Five new species are described: Bursachitina praedolioliformis n. sp., Cyathochitina triangula n. sp., Plectochitina triplesiensis n. sp., Plectochitina anulata n. sp., and Anthochitina admirabilis n. sp. We formalise B. praedolioliformis as a smooth-walled precursor of Eisenackitina dolioliformis. We recognise a distinct faunal turnover at the onset of the late Aeronian event, notably represented by the appearance and radiation of diverse, highly ornamented species. This contrasts with the extinction of marine life we expected to see, based on the documented diversity loss at the onset of other Silurian events.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".